Corona streamer onset as an optimization criterion for design of high voltage hardware on transmission lines

To design hardware for compact high voltage lines, it is necessary to predict conditions for which corona streamers are initiated. Existing techniques for optimizing hardware shape and calculating streamer onset are based on corona measurements in a coaxial geometry that uses concentric cylinders for electrodes. Peek's law shows that the formation of corona streamers is related not only to electric field but also to surface curvature. It is not clear that Peek's law (developed in a coaxial geometry for which radius of curvature in the axial direction is infinite) is appropriate for designing hardware surfaces which are defined at any point by two finite radii of curvature. In this work, the authors seek a corona onset criterion for these more general surfaces which reduces to Peek's law in the limit that one of the radii of curvature is infinite. An existing electrostatic code is being modified to allow for iterative optimization of electrode shapes based on results of previous field calculations. Experimental corona performance testing of electrode shapes will take place in an air-filled chamber with AC voltages as high as 100 kV RMS. Experiments will be used to evaluate various electrode shapes designed by the trial optimization criterion.